An Experimental Study Of The Effects And Mechanism Of CNTF On The Recovery Of Spinal Cord Injury In Rats

Paraplegia below the level of injury resulted from traumatic spinal cord injury (SCI) is one of the tough problems in the world, which is still lack of effective method in clinical treatment. Since increased levels of neurotrophic factors and cytokines may promote neuronal survival and axonal growth, many studies have revealed the administration of exogenous growth factors following SCI rescues the neuronal death and enhances functional recovery. Although the administration of exogenous neurotrophic proteins has therapeutic potential, the limitations imposed by short serum half-life, large molecular weight, high cost and the blood-brain barrier could restrict the clinic utility of this approach.Ciliary neurotrophic factor (CNTF) is a 23kDa cytoplasmic protein that was originally described as a trophic factor supporting the survival of ciliary ganglion neurons in vitro. It can promote the survival and differentiation of a variety of neuronal and glial cells, including motor, autonomic and sensory neurons, hippocampal neurons and oligo-dendrocytes in vivo and in vitro. Especially after injury in the central nervous system (CNS) or peripheral nervous system (PNS), CNTF which is mainly produced by both Schwann cells and reactive astrocytes would ameliorates cell loss or degeneration of injured neurons. Previous study has demonstrated that CNTF can surport the survival of motoneurons and neurite outgrowth from spinal cord neurons in vitro. Following SCI, the level of CNTF that is mainly produced by reactive astrocytes and its receptors that mainly located on motoneurons increased. Accordingly, it has stimulated an interest as potential therapeutic agent for the treatment of spinal cord injury.In our study, we first investigated the neurotrophic effects of CNTF on the survival and differentiation of mouse spinal cord neurons, astrocytes and microglia in cell culture by 3-(4,5-dimethylthiazoil)-2-l-2,5-diphenyltetrazolium (MTT) assays and immunocy-tochemistry staining. Secondly, we investigated the effects of a continuous inthathecal infusion of exogenous CNTF on neuronal loss in the red nucleus neuron (RN) by using a moderate contusive SCI model in adult rat. Thirdly, we assessed the tissue sparing and reactive gliosis at the injury site by histological assess. In addition, we observed the effect of CNTF on the functional recovery of the rats after SCI by behavioral tests.The main results of our research are as follows:(1) Survival-promoting activity of CNTF on spinal cord neurons after 7 days in primary cell culture were estimated by MTT assays. CNTF exhibit dose-dependent survival effects with EDI 00 of 10 ng/ml. The comparisons of the ED100 of CNTF shows that CNTF support the neuron more effectively than controls (P